(1) Field of the Invention
This invention relates to a process for the reduction of acrylamide formation in starchy foods when cooked at high temperature, particularly when they are baked or fried. This invention particularly addresses the problem of acrylamide formation in cooked starchy foods, generally baked or fried at temperatures above 120° C., particularly those selected from the group consisting of chips, tortilla chips, pretzels, crackers, backed goods, fried breads, processed cereals, and French fries. The process of this invention uses microbial cell fermentation to reduce acrylamide precursors (comprising mono- and di-saccharides and others) found in starchy foods prior to cooking. In particular, the present invention relates to a method wherein an uncooked starchy food product is treated with fermentative food grade bacteria and/or yeast under controlled pH and temperatures in the presence of growth stimulants comprising yeast extract and neutralizing agents comprising alkali metal hydroxide (Na or K) or food grade acid (citric, lactic, or hydrochloric).
(2) Description of the Prior Art
The use of acid producing bacterial cultures for food fermentations is well known. In general, the foods are preserved and a flavor is imparted to the food by the acid. The cultures are used for cheese, sausage, cottage cheese, yogurt and the like. Lactic acid is a primary metabolic product and is derived from sugars in the food. The cultures are sold commercially by multiple companies in lyophilized or frozen form. There is less lag time in beginning the fermentation in using the frozen cultures, which are thawed before use, and they are generally preferred. The concentrates usually contain 1010 to 1012 CFU per ml or gram of active bacteria.
The use of yeast in food fermentations is also well known. The yeasts are used in baked goods and beer. Generally the cultures are sold in packets which are refrigerated before use in order to preserve the yeasts.
The U.S. Environmental Protection Agency (EPA) classifies acrylamide, a colorless, crystalline solid, as a medium hazard probable human carcinogen. According to the International Agency for Research on Cancer, acrylamide induces gene mutations and has been found in animal tests to cause benign and malignant stomach tumors. It is also known to cause damage to the central and peripheral nervous system. Acrylamide became a source of debate in April 2002, (Science 297 27 (2002)) when Swedish researchers announced that the chemical was present at high levels in starch-based foods that were fried or baked at temperatures higher than 120° C. They found that acrylamide levels in potato chips, French fries, bread and processed cereals are often hundreds of times higher than the maximum level, 0.5 μg per liter, considered safe for drinking water by World Health Organization (WHO) and the U.S.EPA. The highest levels were found in potato chips (a median of 1,200 ppb) and French fries (450 ppb). Subsequent studies in Norway, Switzerland, the U.K., and the U.S. confirmed the results. Meanwhile, the Food and Drug Administration (FDA) and other world health agencies are drafting action plans to assess human dietary exposures to acrylamide, gathering information about its toxicology, and asking the food industry to develop techniques for reducing its formation in food.
The detailed reaction mechanism for the formation of acrylamide involves the reaction of a sugar such as glucose and asparagine. Potatoes in particular contain significant amounts of free asparagine.
Acrylamide was not found in boiled or uncooked starchy foods; therefore, it is a by-product of high-temperature cooking processes. Different cooking times and temperatures could give rise to the variability of acrylamide levels in foods. Frying foods such as French fries or chips at low temperatures (less than 120° C.) might reduce the formation of acrylamide, but this is very detrimental to the texture and flavor. Frying foods at regular frying temperatures (176-190° C.) for a very short period of time might reduce the formation of acrylamide, but these conditions are also very detrimental to the flavor and texture. Moreover, all food must be cooked properly to destroy food poisoning bacteria. Therefore, the prior art has recognized the need for methods to reduce the formation of acrylamide in cooked starch foods that are safe and not detrimental to the flavor and texture.
Objects
It is an object of the present invention to provide a method for the reduction of acrylamide formation in cooked starchy foods without altering their regular cooking process parameters (temperature and time). Further, it is an object of the present invention to reduce acrylamide precursors found in starchy foods prior to cooking using microbial cell fermentation. Further still, it is an object of the present invention to provide methods that are inexpensive to perform, which preserve the flavor and texture of the cooked starchy food and which can be easily scaled-up to large volumes using conventionally available equipment. These and other objects will become increasingly apparent by reference to the following discussion and drawings.